Tribunal officials say Slobodan Milosevic was found lifeless on his bed in his cell on Saturday.
He was the first head of state to stand trial. He apparently died of natural causes. He was in poor health, suffering from high blood pressure and heart problems, and his trial at the U.N. war crimes tribunal was repeatedly postponed as a result.
But he insisted on defending himself against the charges at the tribunal, which he called false.
"I consider this tribunal a false tribunal, and the indictments false indictments," Milosevic said.
In an effort to keep him healthy, tribunal judges cut back his court hours. The 64-year-old had been on trial for four years in The Hague for leading the former Yugoslavia into war.
Mr. Milosevic used up most of the time allotted to him for his defense, although he had yet to deal with the majority of charges against him. He focused on the charges related to the Serbian province of Kosovo, and did not deal with the genocide charges relating to the 1995 Srebrenica massacres in Bosnia-Herzegovina.
His death means his case is closed. This is a huge blow for both victims and the tribunal, which will never pass judgment on the man they say is most responsible for the wars in former Yugoslavia.